1. Field of the Invention
The present invention relates to a machine component, particularly a bearing component such as, for example, a rolling element or an inner or outer bearing ring in a bearing assembly and a superfinishing method for superfinishing the machine component or the bearing component.
2. Description of Related Art
The conventional superfinishing technique is a post machining technique after grinding a work and is carried out with a non-rotatable grindstone oscillated at the work to thereby improve the surface roughness of the work. The Patent Document 1 listed below discloses a machining method in which the use is made of a superfinishing grindstone to form a crowning in a minute protrusion appearing on a surface of a cylindrical rolling element. The Patent Document 2 listed below discloses a method of and an apparatus for superfinishing an outer peripheral surface of a spherical roller that is used in a self-aligning roller bearing assembly. Also, the Patent Documents 3 and 4 listed below disclose a method of or an apparatus for superfinishing a bearing ring, which is either an inner ring or an outer ring used in a roller bearing assembly. In addition, the Patent Document 5 listed below discloses a technique, in which during the manufacture of a self-aligning roller bearing assembly, machining conditions for the formation of an outer ring raceway are set up to thereby suppress friction and heat emission brought about by skew of each of the spherical rollers employed in the bearing assembly.
FIG. 7 illustrates conceptually one example of a manner for superfinishing a peripheral surface of a cylindrical work to be machined with the use of a grindstone. Referring to FIG. 7, while the work 100 to be machined is rotated about its own longitudinal axis in a direction shown by the arrow 100A, the grindstone 101 is worked on the work 100 to traverse in a direction shown by the arrow 101A, which is parallel to the longitudinal axis of the work 100, relative to the work 100 to thereby superfinish the peripheral surface of the work 100.